This dataset is associated with the article by Marine Pacé, Nicole J. Fenton, David Paré and Yves Bergeron entitled "Differential effects of feather and Sphagnum spp. mosses on black spruce germination and growth". It includes data of black spruce germination (greenhouse), seedling growth (0 to 6 months, greenhouse) and sapling growth (2-3 years, greenhouse and field, 49°44’N, 79°17’W). Seeds, seedlings and saplings were subjected to different treatments: 3 types of ground cover (bare soil, feather mosses, Sphagnum spp. mosses), different levels of fertilization, and different levels of shade above the moss layer. The dataset also contains information on the chemical composition (N, P, K, Ca, Mg, Na, cation base) of the first centimeters of soil below the moss layer (data for greenhouse and field experiments).